AD-776 230

THE INCIDENCE OF VESTIBULAR SYMPTOMA- TOLOGY IN 2,500 U.S. NAVY DIVING ACCIDENTS (1933-1970)

Robert S. Kennedy, et al

Naval Medical Research Institute

Prepared for:

Bureau of Medicine and Surgery

January 1974

DISTRIBUTED BY:

KUn National Technical Information Service U. S. DEPARTMENT OF COMMERCE 5285 Port Royal Road, Springfield Va. 22151

THE INCIDENCE OF VESTIBULAR SYMPTOMATOLOGY IN 2,500 U.S. NAVY DIVING ACCIDENTS (1933-1970)

Robert S. Kennedy LCDR, MSC, USN

and

Joseph A. Diachenko

Behavioral Sciences Department Naval Medical Research Institute National Naval Medical Center

Bethesda, Maryland 20014

January 1974

ABSTRACT

The U.S. Navy divinp accident records (2,500 cases) for the years

1933 Co 1970 were analyzed and sorted Into Type I and Type II decom-

pression sickness. Type II was further sorted into "vestibular" and

"other" categories. It was concluded that Type II symptoms accounted

for 30% of the decompression accidents and it was estimated that Che

overall incidence of vestibular symptomatology was between 10 and 20%,

Nearly 30% of Che Type II cases were diagnosed as having vestibular

involvement, although almost 60% of the cases contained a report of a

symptom typically associated with the vestibular system complex

(e.g., dizziness and nausea).

KLY W0PJ)S

Diving accidents

Vestibular symptomatology

Decompression sickness

Type I

Type II

Vertigo

Dizziness

Nausea

Ataxla

Vision

Hearing

Joint pain

UNCLASST1 /)-D ??^ a^o

NAVAL MEDICAL RESEARCH INSTITUTE BETHESDA, MD. 20014

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THE INCIDENCE OF VESTIBULAR SYMPTOMATOLOGY IN 2,500 U.S. NAVY DIVING ACCIDENTS (1933-1970)

DCSCftiPT v t" NOTES ffyp« <jt report tuni, im in-, i \ f J.IM-., ,

MEDICAL RESEARCH PROGRESS REPORT [T ATTTTTOR i i>' {Fin.f nttrnr. middle initial, las: r.^m- /

i Robert S. Kennedy and Joseph A. Diachenko

6 RE POR T C A T L

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Benavioral Sciences Department 1 National Naval Medical Center * Bethesda, Md. 20014

BUREAU OF MEDICINE AND SURGERY (NAVY) WASHINGTON, D.C. 20372

13 ABSTRACT

The U.S. Navy diving accident records (2,500 cases) for the i years 1933 to 1970 were analyzed and sorted into Tvpe I and Tvpe II ; decomnression sickness. Tvpe II was further sorted into "vestibular"| and "other" categories. It was concluded that Tvpe II svirmtoms ac- counted for 30% of the decompression accidents and it was estimated j

■ that the overall incidence of vestibular symptomatologv was between 10 and 20%. Nearly 30% of the Tvpe II cases were diagnosed as havinc« vestibular involvement, although almost 60% of the cases contained a report of a symptom typically associated with the vestibular system' complex (e.g., dizziness and nausea).

DD.Fr65l473 S/\ 0102-014-6700

;PA&E i) UNCLf >xt it

S('< unl' Cld^SificjUon

UNCLASSIFIED Security Ctaiilficatton

HBV WORDS

1. Diving accidents

2. Vestibular sympatomatology

3. Decompression sickness

4. Type I

5. Type II

6. Vertigo

7. Dizziness

8. Nausea

9. Ataxia

MO. Vision

11. Hearing

12. Joint pain

LINK A

MOLE ROLC , WT

DD.!:oor..U73 «/N •!•»•• 4*Me /^_

UNCLASSIFIED Security CUitlfieatten *• tue*

CONTENTS

Page No.

Abstract and Key Words 1

Introduction 1

Method and Procedure 2

Results 4

Discussion 10

References 14

List of Illustrations and Tables

Table 1. Incidence of Vestlbular Decompression Sickness Accidents In Total Number Reviewed. . . 4

Table 2. Distribution of Type I, Type II, and Vestlbular DCS Cases, 1945-1970 5

Table 3. Summary of Reported Symptomatology for 457 Navy Type II DCS Cases, 1945-1970 9

Table 4. A Comparison of Absolute (number) and Relative (proportions) Incidences of Various Diagnostic Categories of Decompression Sickness 10

Fig. 1. Proportion of Vestlbular DCS to Total DCS, 1945-1970 7

Fig. 2. Proportion of Type II DCS to Total DCS, 1945-1970 8

ii

THE INCIDENCE OF VESTIBULAll SYMPTOMATOLOGY* IN 2,500 U.S. NAVY DIVING ACCIDENTS (1933-1970)

** *** Robert S. Kennedy and Joseph A. Dlachenko

INTRODUCTION

Decompression sickness (DCS) has always bcea one of the main occu-

pational hazards of divers and tunnel workers. The most frequently

reported symptom, joint pain, is considered the chief symptom of the malady,

and occasionally a diagnosis of DCS will not be made unless joint pain

is present. Furthermore, while U.S. Navy diving tables are predicated

on th« theory of the solubility of gases, they have also been empirically

validated against a criterion of freedom from symptoms, particularly

freedom from Joint pain. Historically, however, in addition to pain,

other symptoms have been shown to occur in connection with decompression

sickness, and many of these symptoms are generally considered to reflect

central nervous system involvement. One of these symptoms (vertigo)

generally indicates involvement of the vestibular apparatus. Its neural

pathways or central projections.

A recent annotated bibliography of vestibular problems in diving

revealed that, particularly among the earlier writers, after Joint pain,

* From Bureau of Medicine and Surgery, Navy Department, Research

Subtask MA306.03.300ÜBAK9. The opinions and statements contained herein are the private ones of the writers and are not to be construed as offi- cial or reflecting the views of the Navy Department or the naval service at large.

** LCDR Kennedy is now Head, Human Factors Engineering Branch, Naval

Missile Center, Point Mugu, CA 93042.

Mr. Dlachenko is now on the staff of the Uiomedical Research Laboratory, Naval Weapons Laboratory, Dahlgren, VA 22448.

K«nn«dy 2

•ar problems were the next most frequently mentioned symptom complexes.

A review of this work is available. Rubenstein and Summitt,^ in a

review of ten years of Navy diving accidents, showed that even by using

a conservative criterion of vestibular involvement (i.e., vertigo, as

opposed to all vestibular symptoms) the proportion of vestibular embar-

assment was increasing in their recent diving experiences.

Since it is known clinically that other symptoms can also result

from vestibular involvement, perhaps a review of Navy diving accidents

with the intention of including these other symptoms would be advisable.

Because so much attention has been paid to Joint pain in connection with

decompression sickness, and because symptoms other than vertigo (but nor-

mally associated with vestibular stimulation) were not considered together

In previous epidemiologic reports, * ' * it was hypothesized that involv-

oent of Che vestibular system was previously underestimated.

The purpose of this study is to report in a general way the incidence

of vestibular involvement in Navy diving accidents. A more complete and

speculstive coverage of these data, including relationships between cons-

titutional factors and type of decompression sickness, as well as selected

case histories, will appear later. ' '

METHOD AND PROCEDURE

A total of 2,502 diving accidents logged by the U.S. Navy between

1933 and 1970 were individually read by one of the authors to obtain an

outline of sach case showing: diver age, height, weight, depth, bottom

tine, equipment, gas, and type of accident. The symptoms of DCS were

studied to identify each case as a Type I or Type II hit according to

3 Kennedy

Che classification system of Golding, Griffiths, llenpleman, Paton, and

Wälder5 where:

Type 1 ■ pain, skin rash, or local lymphatic occlusion;

Type II ■ dizziness, confusion, disorientation, nystagmus, visual

signs (diplopia, tunnel vision, et cetera), sensory

impairment (paraesthesia, numbness), motor weakness or

loss, nausea, dyspnea, and other central nervous system

involvements.

Those cases identified as Type II were further sorted regarding the

Incidence of symptoms typically manifested by vestibular embarassment:

dizziness, vertigo, nausea, nystagmus, disequilibrium, certain visual

phenomena, acoustic aura, and disorientation. The following criteria

were employed to clarify a Type II case as having vestibular involvement:

1. Diagnosis of presiding medical officer as a labyrinthine problem.

Inner ear or middle ear embolism, vestibular hit, et cetera.'

2. A combination of symptoms sich as dizziness and nausea with dis-

equilibrium, nystagmus, and visual or acoustic aura with gait problems,

et cetera.

3. Dizziness and nausea with supportive reporting In Che narrative

Co warrant a reasonable assumption of vestibular involvement, such as

persistent dizziness during treatnent, precipitated by changes in body

position (positional vertigo).

4. Vertigo.

Kenntdy 4

RESULTS

A total of 2,502 case reports were reviewed and these data appear

as Table 1. Case» reported between 1933 and 1944 were dropped because

It was felt that record keeping was imperfect during the early stages of

diving recording from the standpoint of their use in establishing base

rat« data. This left 2,349 cases, or roughly 100/year between 1945 and

1970. Of these, about one-fourth were civilian cases and these too were

dropped since it was felt they were not representative of U.S. Navy diving

accidents. They are of some interest, however, and selected civilian

case histories will be reported elsewhere. Casej which were clearly not

decompression sickness (e.g., air embolism, equipment problems, baro-

traumatle otitis media [cf. ref. 8, pp. 4, 12, 14], oxygen toxiclty) were

also removed from consideration. Thus, a total of 1,530 Navy DCS diving

accidents remained. Of these, two-thirds were considered Type I and one-

third Type II, a slightly higher percentage than was previously reported.

Table 1 shows that vestibular accidents comprise about 27% of the

total Type II accidents, and about 10% of all the DCS accidents.

Table 1

Incidence of Vestibular Decompression Sickness Accidents in Total Number Reviewed

Total Accidents Reviewed 2,502 Less 1933-1944 cases _jiU3

Total Accidents 1943-1970 2,349' Less Civilian Cases _ -470

Total Navy cases 1945-1970 1,'8Y9 Less Toxicity and Others (non-DCS) _ -349

Total Navy DCS Cases 1945-1970 1,530 Less Type I (pain) -li0_73

Total Type II, Navy 1945-1970 ' 457 Less Non-Vestibular DCS __li.33

Total Vestibular DCS, Navy 12'4

5 Kennedy

Table 2 shows the relative number of Type I or Type II accidents

over the period 1945-1970, with a further breakout of vestlbular accidents.

Graphically presented In Figure 1 and Figure 2 as proportions, are the

data from Table 2.

Table 2

Distribution of Type I, Type II, and Vestlbular DCS Cases 19A5-1970

Type II Type I Total DCS

Year Vestlbular Non-Vestlbular Total

1970 16 19 38 57 1969 16 20 30 50 1968 14 21 58 79 1967 11 13 48 61 1966 15 19 40 59 1965 17 26 18 44 1964 18 26 21 47 1963 13 15 28 40 68 1962 23 28 24 . 52 1961 23 26 35 61 1960 24 30 69 99 1959 19 21 65 86 1958 10 16 41 57 1957 4 8 35 43 1956 19 27 69 96 1955 7 15 21 36 1954 15 22 67 89 . 1953 12 17 33 50 1952 9 15 40 55 1951 3 5 28 33 1950 6 8 33 41 1949 8 11 24 35 1948 5 5 20 25 1947 7 8 42 50 1946 9 12 68 80 1945 8 11 66 77

Kcnnady 6

Figur« 1 fthovs Che overall Incidence of vestibular accidents In

several ways: (1) the grand mean Is about 8% of all DCS accidents for

the 26-year period although vestibular embarassment ranges from more

than 15% In some years to as low as xero to 2% in others: (2) a running

mean (3-year base) and a 5-year mean reflect similar functions, namely,

a generally Increasing Incidence of vestibular problems over the years,

with paak percentages during 1960-1965 and then a reversal of this trend.

Figure 2 shows the relationship of Type II DCS to total DCS

(I.e., Type I plus Type II). The overall percentage is 30% or a ratio

of about 2:1 for Type I to Type II. Over these years the proportion of

Type ZZ DCS appeared to be increasing up to 1960-1965 and at times the

incidence of Type II symptomatology exceeded Type I reports (vix., in

1962, 1964, and 1965). For the last five years for which data is avail-

able (1966-1970), the ratio is more in agreement with the 26-year average

(I.e., 2:1 for Type I:Type II).

Table 3 shows the number of times that each symptom category was

employed in the 457 Type II cases, as well as the percentage occurrences

of each. The most frequently reported vestlbular-type symptom was dix-

xlness, which appeared on nearly one-third of the Type II accident forms.

The least often reported vestibular symptom was nystagmus. Of the 457

eases, at least one vestlbular-type symptom was reported on more than

half of the forms (N-268)*. For nonvestibular-type symptom categories

•This is a liberal criterion for vestibular involvement since It is not slways possible to determine with confidence whether dixslness or visual anomalies are due to vestibular or other causes.

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9 Kennedy

''weakness, paraesthesla, and numbness" was mentioned most and about as

often as dizziness.

Table 3

Summary of Reported Symptomatology for 457 Na/y Type 11 DCS Cases 1945-1970

Symptom Number* Reporting Percentage Symptom Occurrence

Dizzy 141 30% Vertigo 19 42 Nausea 111 247. Nystagmus 11 2% Disequilibrium 15 3% Hearing 32 77. Vision 97 21% Dlsorientation 19 6% 1 or More Vestibular 263 59%

Non-Vestibular 189 41%

• N - 457

Table 4 summarizes in compact form the incidence of the diagnostic

classifications listed variously above, and the relative incidences appear

in matrix form. It may be seen that vestibular involvement makes up 91

of the total DCS and 28% of the Type II. Noteworthy, however, is the

fact that when a liberal criterion is employed regarding vestibular

Involvement (i.e., any vestibular-type symptom reported), then vestibular

Incidence doubles with respect to the total DCS as well as to Type II

DCS. The proportion of Type II DCS to the total is shown to be 33%.

Ktnnsdy 10

Table 4.

A Comparison of Absolute (number) and Relative (proportions) Incidences of Various Diagnostic Categories of Decompression Sickness

No. of Cases _!_

Proportions 2 3 4

1. Vestibular DCS 124 x 46%t 27% 8%

2. Potential Vestibular* 268 x X 59% 18%

3. Total Type II DCS 457 _x_

1,530 x

X X

X

30%

4. Total DCS X X

reported. * Any one or more vestibular typ'i symptoms

t Proportion of 1:2 ■ 124 - 26"8

46%

DISCUSSION

The data reported here suggest that the overall incidence of vestib-

ular decompression sickness is higher than most previous reports indica-

ted, being between 10-20% depending on whether a conservative or liberal

criterion Is employed. Additionally, the incidence of central nervous

system forms of decompression sickness (33%) also appear to be somewhat

higher than has been reported by others. The higher proportions found

In this study are due partly to the fact that they were specifically

selected for study and so the authors were poised to see these relation-

ships when they occurred. Additionally, it Is felt that another reason

for the higher incidences reported Is that the entire narrative was read

for each form, rather than Just a tally of the reported symptoms. Often,

localised pain was the only symptom checked on the foim; however, other

•ya^toas were described in the text by the diving medical officer. For

11 Kennedy

this reason, it Is felt Chat Che data reported here probably do not

overstate the case—indeed, it is probable that the incidence may be

even higher for the following reasons:

1. In compressed gas work, dizziness, nausea, vertigo and vomiting,

and occasionally ataxia, are considered as vcstibular symptoms although

only vertigo is generally discussed. However, other symptoms also occur

from stimulation to the vestibular system. These include drowsiness,

pallor, sweating, salivation, as well as various sorts of visual phenomena

(e.g., nyotagmus, apparent movement) and should be considered in studying

vestibular involvement.

2. Central nervous system (CNS) symptoms, when they develop, are less

tangible than pain and may be ignored, not considered manly, or part-

ly controlled (e.g., keeping the head still may minimize vertigo). Thus

a person who may present with pain and respond to treatment may have had

CNS symptoms earlier, which are missed later during the treatment of

the pain.

3. Most of the diver accident records previously used by the U.S.

Navy contained physically a broad space in which to record pain-type symp-

toms, thus the physician is encouraged by the layout of the form to add

descriptive comments for pain on the form beside the time it occurred.

However, he is enjoined from doing this for vestibular-type symptoms since

the space beside dizziness, vertigo, et cetera are blackened out.

4. There may be a tendency to consider Type I and Type II symptoms

of DCS as mutually exclusive categories (See McCallum for a review of

DCS studies reported between 1914-1966). Therefore, if a person reported

K«nn«dy 12

ttvtrt pain and mild dizziness, there might be a tendency to classify

this as Type I. Further, the tangibility of the pain-type symptoms, with

probable higher cure rate, may also cause It to be favored as a diagnostic

category.

5. Provocative tests of Eustachlan tube clearing at 50 pounds per

•quart Inch arc conducted prior to Navy diver training, * but not neces-

sarily prior to civilian Scuba training. If Eustachlan tube patency is

negatively related to a susceptibility to vertigo, then other things

being equal, data from Navy diver records may underestimate the problem

when generalized to include the potential Incidence of vestlbular problems

In all diving.

6. Because a form of apparent movement is experienced less by alcho-

lica and because a "fullness of habit" (Van Rensselaer15 and others)

is cooaon in compressed air workers, then perhaps experiences of vertigo

in career divers may be less in these groups than in sport divers.*

Q Other reasons are suggested in Kennedy.

In sumnary, it is felt that the incidence of vestlbular embarassnent

in U.S. Navy compressed gas work is higher than was previously realized.

Moreover, it is likely to have been higher than is reported here. 'It

should be noted that this, plus other factors, suggest that an even

higher incidence may occur in civilian diving accidents.

*This factor may be a training or natural selection variable since a high fluid exchange rate may be a consequence of "fullness of habit." But—a high fluid exchange rate has also been shown to afford some pro- tection from decompression sickness (Warwick^»1**).

13 Kennedy

An additional finding of interest emerged from this study regarding

diver accident reporting procedures. Since the total population of dives

conducted during the 1945-1970 period remains unknown, the incidence of

vestlbular involvement reported here is only an approximation. True

incidence will soon be measurable through the use of the new computer-

compatible, dive-log accident form in use since 1970.

However, in regard to the new reporting form it must be pointed

out that while the new form offers a significant inprovement over the

old DU Form 816, the improvement is entirely on the side of easier access

to quantified data. Qualitative, narrative reporting is no more encour-

aged than on the old form. Reporting the sequence and character of

symptomatology offers a wealth of information that is lost in the process

of listing symptoms out of context, and the new form presents a formidable

task of check-list itemizing with only a little space, and no emphasis

on the importance of a chronological narrative.

Kennedy 14

REFERENCES

1. Diechenko, J. A. Civilian diving accidents treated by the U.S. Navy, 1945-1970. In preparation.

2. Diachenko. J. A., and R. S. Kennedy. The relationship of consti- tutional factors and age to Type I and Type II decompression illness. In preparation.

3. Doll, R. E. Decompression sickness among U.S. Navy operational divers: An estimate of incidence using decompression tables. U.S. Navy Experimental Diving Unit, Wash., D.C., Report No. 4-64, February, 1963.

4. Doll, R. E., and T. E. Berghage. Interrelationships of several parameters of decompression sickness. U.S. Navy Experimental Diving Unit, Wash., D.C., Report No. 7-65, March 1967.

5. Golding, F. C, P. D. Griffiths, H. V. Hempleman, W. D. M. Paton, and D. N. Wälder. Decompression sickness during construction of the Dartford Tunnel. Br. J. Ind. Med. 17:167-130, 1960.

6. Keays, F. L. Compressed air illness with a report of 3,692 cases. Cornell University Medical College, Ithaca, New York. Researches from the Department of Medicine, October 1909.

7. Kennedy, R. S. A bibliography of the role of the vestibular apparatus under water and pressure: Content-oriented, and annotated. Naval Medical Research Institute Report No. 1, MA306.03.5000BAK9, Bethesda, Md., August 1972.

8. Kennedy, R. S. The role of the vestibular apparatus under water and high pressure. Naval Medical Research Institute Report No. 3, M4306.03.5000ßAK9, Bethesda, Md., March 1973a.

9. Kennedy, R. S. General history of vestibular disorders In diving. Naval Medical Research Institute Report No. 4, MA306.03.5000BAK9, Bethesda, Md., December 1973b.

10. Kennedy, R. S,, J. A. Diachenko, and M. Sherman. Selected cases of vestibular hits in diving: Character and chronology of symptoms. In preparation.

11. McCallum, R. I. Decompression sickness: A review. Br. J. Ind. Med. 24:4-21, I960.

12. Rivera, J. C. Decompression sickness among divers: An analysis of 935 cases. U.S. Navy Experimental Diving Unit, Wash., D.C., Report No. 1-63, February 1963.

15 Kennedy

13. Rubenstein, C. J., and J. K. Summitt. Vestlbular derangnent In decompression. In C. J. Lambercsen (Ed.) Underwater physiology, pp. 287-292. New York: Academic Press, 1971.

14. Shilling, C. W. Aero-otltis media and auditory acuity loss in submarine escape training. Trans. Am. Acad. Ophthalmol. Otolaryngol. 49:97-102, 1944-45.

15. Van Rensselaer, H. The pathology of the caisson disease. Trans. N.Y. State Med. Soc. pp. 408-444, 1891.

16. Voth, A. C. Autoklnesls and alcoholism. (£. J. Stud. Alcohol 26(3):412-422, 1965.

17. Warwick, 0. H. The apparent relationship of fluid balance to the Incidence of decompression sickness. No. 2 Clinical Investigation Unit, RCAF, Regina. Report to NRC, April 1942.

18. Warwick, 0. H. Further studies on the relationship of fluid intake and output to the incidence of decompression sickness. Flying Personnel Medical Section. No. 1 "Y" Depot, RCAF, Halifax. Report to NRC, February 1943.